Osteochondral allografts

ABSTRACT

Provided are procedures and instruments for preparing and transplanting osteochondral allograft plugs to a host bone to repair an articular cartilage defect. An allograft bone plug having a cartilage plate and cancellous bone tissue attached thereto is removed from a donor bone. The allograft plug is further shaped by removing or cutting away cancellous bone tissue to form a cancellous stalk extending from the cartilage plate. The formed cancellous stalk can have any suitable shape including cylindrical, conical, and rectilinear. At the recipient site of the host bone, a cutout is formed corresponding in shape to the allograft plug. The allograft plug is inserted into the cutout such that the cancellous stalk is retained in the host bone and the cartilage plate aligns with the condyle surface of the host bone. Aspects of the invention may also be applicable to preparing and transplanting osteochondral autograft plugs.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application is a divisional application of copending U.S.patent application Ser. No. 11/259,749, filed Oct. 26, 2005, thedisclosure of which is herein incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

In humans and many other animals, cartilage is present on the surface ofbones that form articular joints to facilitate articulation of the jointand protect and cushion the bones. However, defects may develop in thecartilage from various causes such as abrupt trauma or prolonged wear. Anumber of techniques have been attempted to treat such cartilagedefects. One such technique is the transplantation of freshosteochondral allografts.

In this procedure, an allograft plug, also known as a osteochondral plugor core, is harvested from a condyle or rounded joint-forming portion ofa donor bone. Intact on the surface of the allograft plug, on a portionof the bone known as the cartilage plate, is healthy cartilage. Theallograft plug may also have attached to the cartilage plate cancelloustissue, which is the porous inner material that is present in manybones. In the recipient patient, the cartilage defect and thecorresponding portion of underlying bone are cutaway and removed fromthe joint. The allograft plug is then inserted and attached to thecutaway portion so that the cartilage plate and healthy cartilage of theallograft plug align with the cartilage on the surface of the host bone.

One problem that arises with osteochondral allografts is that therecipient may adversely respond or reject the allograft plug. This canhappen primarily because of the antigenic material contained in thecancellous bone of the allograft plug. Occurrence of such an adverseresponse may result in the recipient site reforming or healing in such amanner that the allograft plug becomes walled off from the host bonethereby delaying or preventing incorporation of the allograft. Inaddition, physically attaching and securing the allograft plug to therecipient site presents difficulties.

BRIEF SUMMARY OF THE INVENTION

The invention provides methods and instruments for preparing andtransplanting osteochondral allografts to repair articular cartilagedefects. According to one aspect of the invention, an allograft plughaving a cartilage plate and cancellous bone tissue attached thereto isremoved from a donor bone. The allograft plug is further shaped byremoving or cutting away cancellous bone tissue to form a cancellousstalk extending from the cartilage plate. The formed cancellous stalkcan have any suitable shape including cylindrical, conical, andrectilinear. According to another aspect of the invention, in what willbecome the host bone of the patient, a recipient site is prepared byforming a cutout corresponding to the cartilage defect. The shape of thecutout generally corresponds to the shape of a provided allograft plugfrom which cancellous material has been removed to form a cancellousstalk. The allograft plug is inserted into the cutout such that thecancellous stalk is retained in the host bone and the cartilage platealigns with the condyle surface of the host bone. Removing and shapingthe allograft plug can be performed separately or together withpreparing a recipient site by forming a cutout and inserting theallograft plug into the cutout.

To prepare the recipient site, a template can be attached to the hostbone in a location corresponding to the cartilage defect. In an aspectof the invention, the template can include a guide aperture disposedtherein. To facilitate alignment of subsequent operations, an elongatedguide pin is inserted through the guide aperture and into the host bone.Cannulated drill bits having the desired shape can be slid over theguide pin and driven into the host bone to form the shaped cutout. Inanother aspect of the invention, the template can include a plurality ofcut slots disposed therein. A cutting device can then be insertedthrough the cut slots and into the host bone to form the shaped cutout.

To remove and shape the allograft plug from the donor site, a secondtemplate specially adapted to attach to the donor bone can be used. Oneadvantage of employing a template to remove the allograft plug is thattemplate may facilitate simultaneous shaping of the allograft plug atthe time of removal. In other embodiments, the allograft plug caninitially be a piece of cylindrically or otherwise shaped bone materialremoved from the donor bone and subsequently shaped to produce thefinished allograft plug.

It should be recognized that various aspects of the invention may alsobe applicable to preparing and transplanting an osteochondral autograftplug, a process which involves removing a plug from a first location andtransplanting the plug into a second location within the same patient.

The invention provides one or more of the following advantages: Anadvantage of the invention is that it provides a osteochondral allograftplug that has a reduced amount of cancellous tissue and is thereforeless likely to be rejected by a recipient. Another advantage is that itprovides a specially shaped osteochondral allograft plug that can be fitand anchored into a correspondingly shaped cutout at the recipient site.These and other advantages and features of the invention will beapparent from the detailed description and the accompanying drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a perspective view of a device for removing from a donor bonea transplantable osteochondral allograft plug for repairing a cartilagedefect.

FIG. 2 is a perspective view of an allograft plug shaped in accordancewith an embodiment of the invention, the allograft plug having acartilage plate and a cylindrical cancellous stalk.

FIG. 3 is a perspective view of another embodiment of an allograft plughaving a cartilage plate and a conical cancellous stalk.

FIG. 4 is a perspective view of another embodiment of an allograft plughaving a rectangular shape.

FIG. 5 is a perspective view of another embodiment of an allograft plughaving a triangular shape.

FIG. 6 is a front elevational view of a template for preparing arecipient site in accordance with the teachings of the invention, thetemplate including a central guide aperture.

FIG. 7 is a side elevational view of the template shown in FIG. 6 andfurther illustrating a detachable handle engaged to the template.

FIG. 8 is a perspective view of the template of FIG. 6 attached to thecondyle of host bone in accordance with an embodiment of the invention,the handle being engaged to the template and a guide pin being insertedthrough the template

FIG. 9 is a perspective view of the guide pin inserted into the condyleof the host bone after removal of the template.

FIG. 10 is a side elevational view of another embodiment of a cannulateddrill bit for forming a cutout in a recipient site in accordance with anembodiment of the invention, the drill bit having a counter-bore formingelement and a conical cutting body with a central cannula shown incutaway.

FIG. 11 is a side elevational view of another cannulated drill bit forforming a cutout in a recipient site in accordance with an embodiment ofthe invention, the drill bit having a counter-bore forming element and acylindrical cutting body.

FIG. 12 is a perspective view of the drill bit of FIG. 9 being driveninto the condyle of the host bone to form the cutout.

FIG. 13 is a cross-sectional view taken generally along line A-A of FIG.12 illustrating cutout formed into a recipient site of a condyle of ahost bone.

FIG. 14 is a perspective view of the condyle of a host bone illustratinga method of inserting an shaped allograft plug into a cutout formed at arecipient site using a tamp.

FIG. 15 is a front elevational view of the condyle of a host boneillustrating another method of inserting a shaped allograft plug into acutout formed at a recipient site using a suture.

FIG. 16 is a perspective view of a guide plate with a removable guidecylinder for assisting in removing and shaping a cylindrically shapedallograft plug from a donor bone.

FIG. 17 is a top perspective view of a cannulated burring shell forremoving cancellous material and shaping a conically shaped allograftplug.

FIG. 18 is a cross-sectional view of a sleeve placed about an allograftplug having a cylindrical shaped cancellous stalk and a guide pininserted through the sleeve and partially into the cancellous stalk.

FIG. 19 is a perspective view of a pair of specially configured forcepsfor handling and manipulating a shaped allograft plug.

FIG. 20 is a front elevational view of a template having cut slots forremoving and shaping a rectilinear allograft plug from a donor bone.

FIG. 21 is a cross-sectional view of the template taken along line B-Bof FIG. 20.

FIG. 22 is a cross-sectional view of another embodiment of a template,similar to the template shown in FIGS. 20 and 21, but adapted forpreparing a recipient site on a host bone to receive a rectilinearallograft plug.

DETAILED DESCRIPTION OF THE INVENTION

Now referring to the drawings, wherein like reference numbers refer tolike elements, there is illustrated various processes and instrumentsfor preparing and transplanting an osteochondral allograft in accordancewith the various embodiments of the invention. Referring first to FIG.1, there is shown a device 100 suitable for cutting and forming acylindrically shaped allograft plug 124 from a donor bone 120 inaccordance with one aspect of the invention. The device 100 itselfincludes a clamp assembly 102 and a tubular crown saw 104. The clampassembly 102 includes two vertically extending clamp pads 106, 108, thatcan be moved with respect to each other by rotation of a linear screwmechanism 110. The crown saw 104 is directed towards and linearlymovable with respect to the clamp assembly 102. To align the clampassembly 102 and crown saw 104, the crown saw can pass through avertical alignment plate 112 joined to a base 114 onto which the clampassembly is also mounted.

To produce an allograft plug, a donor bone 120 or a portion thereofhaving on its surface healthy cartilage is received between the clamppads 106, 108 and the clamp pads are moved together to grasp and holdthe donor bone in alignment with the crown saw 104. Preferably, thedonor bone 120 can be received in the clamp assembly 102 such that acondyle 122 corresponding to a donor site on the donor bone 120 ispositioned towards the crown saw 104. The rotating tubular crown saw 104is moved towards and into the donor site 122 to form a cylindrical cutinto the donor bone 120, after which the crown saw can be removed. Thecylindrically shaped bone material 124 produced by the cylindrical cutand that will correspond to the allograft plug can then be removed fromthe remainder of the donor bone 120 by, for example, transecting thedonor bone with a saw or by propagating a crack through the donor bonewith a tamp or similar device.

The removed cylindrical shaped bone material 124 has a cartilage plate126 corresponding to the outer surface of the donor bone 120 and onwhich healthy cartilage is located. Extending from the cartilage plate126 is cancellous bone tissue 128 from the interior portion of the donorbone 120. As will be appreciated by those of skill in the art, whenmaking the cut into the donor site 122, the donor bone 120 and the crownsaw 104 are preferably arranged so that the contour of the cartilageplate 126 corresponds to the portion of the host bone which is to berepaired.

Once the cylindrically cut bone material has been removed, it can beshaped by any variously suitable subsequent shaping operation to removecancellous bone tissue and form a cancellous stalk extending from thecartilage plate. Removing cancellous bone tissue results in thecancellous stalk having a reduced cross section compared to thecross-section of the cartilage plate.

Because the cancellous bone tissue on the allograft plug could containantigenic material, reducing the amount of cancellous bone tissuetransplanted to the host reduces the possibility of an adverse reactionwithin the host. Another advantage of shaping the allograft plug to forma cancellous stalk is that the stalk provides an anchor-like structurethat assists in anchoring the allograft plug into a recipient site onthe host bone. A related advantage is that, by removing cancelloustissue from the cancellous stalk, the amount of cancellous tissue thatmust be accommodated by the host bone during transplantation is reduced.Accordingly, the size of the cutout that must be formed into a recipientsite on the host bone is likewise reduced thereby requiring less traumato the host bone.

The finished allograft plug can have any suitable shape. For example,referring to FIG. 2, there is illustrated an allograft plug 130 having acircular cartilage plate 132 and a cylindrical cancellous stalk 134 ofcancellous bone tissue extending therefrom. The cartilage plate 132 hasa generally circular perimeter of a first diameter and includes healthycartilage from the donor intact on subchondral bone tissue 136. On theunderside of the cartilage plate 132 there may also be a thin layer ofcancellous bone tissue 138 which corresponds to the first diameter. Thecylindrically shaped cancellous stalk 134 extends from the thin layer ofcancellous bone tissue 138 and has a second perimeter or second diameterreduced in size with respect to the first diameter. The reduction insize of the second perimeter compared to the first perimeter is theresult of removing cancellous bone tissue to form the stalk. Preferably,the circular cartilage plate 132 and the cylindrical cancellous stalk134 are coaxial.

Referring to FIG. 3, there is illustrated another embodiment of anallograft plug 140 having circular cartilage plate 142 and a generallyconical cancellous stalk 144 extending therefrom. The cartilage plate142 again has a first perimeter of a given first diameter while theconcial perimeter of the cancellous stalk tapers so as to progressivelyreduce in diameter as the stalk extends from the cartilage plate.Preferably, the circular cartilage plate 142 and the conical cancellousstalk are coaxial. In other embodiments, the cancellous stalk may have astepped shape with each step having a reduced perimeter or diametercompared to the first perimeter of the cartilage plate.

Referring to FIG. 4, there is illustrated another embodiment of anallograft plug 150 having rectangular cartilage plate 152 with atapering or rectangular pyramid-shaped cancellous stalk 154. As will beappreciated, the tapering of the cancellous stalk 154 results in aprogressive reduction of its cross-section with respect to thecross-section of the rectangular cartilage plate 152. Referring to FIG.5, there is illustrated an allograft plug 160 having a triangularcartilage plate 162 and a tapering triangular pyramid-shaped cancellousstalk 164 extending therefrom. In other embodiments, the rectangular andtriangular cartilage plates can have respective rectangular andtriangular cross-sectioned stalks extending therefrom.

To prepare a recipient site in a host bone for receiving the allograftplug, special instruments can be used to form a cutout corresponding inshape to the allograft plug. Such special tools can include, forexample, a template 170 as illustrated in FIGS. 6 and 7. The template170 includes a flat, circular template plate 172 through the center ofwhich is disposed a guide aperture 174. From one surface of the templateplate 172 there projects a short distance a plurality of sharp teeth176. The teeth 176 are preferably arranged in a circular patternconcentric with the circular template plate 172. To enable manipulationof the template 170, the template preferably also includes a detachablehandle 180 that engages a corresponding engagement structure 182 on theopposite surface of the plate 172 from which the teeth 176 project. Thehandle 180 and plate 172 can be engaged by, for example, a twist lockmechanism. In various embodiments, the guide aperture 174 can continuethrough the detachable handle 180 as well. The guide aperture 174 isadapted to receive a guide pin 184 in a sliding fit such that the guidepin 184 can be inserted through the center of the plate 172.

When preparing a recipient site with the template, referring to FIG. 8,a joint such as a knee joint of the patient being treated is firstmanipulated to expose the cartilage defect on the surface of a condyle192 of a host bone 190. Once the cartilage defect is suitably exposed,the template 170 is attached via the sharp, projecting teeth to thecondyle 192 at a location corresponding to the defect. Preferably, tominimize damage, the circular pattern of the teeth projecting from thetemplate corresponds to the area of the defect. Once the template 170 isattached, the detachable handle 180 can be removed and the guide pin 184inserted through the guide aperture 174 and into the host bone 190 atthe location of the defect. Once the guide pin 184 is driven into thehost bone 190, the handle 180 can be reattached to the template 170 andthe template pull over the guide pin and removed from the condyle 192.In other embodiments, the guide pin can be inserted with the handleremaining attached to the template. Thereafter, the guide pin 184remains inserted into the condyle 192 as illustrated in FIG. 9.

To form the cutout that removes the cartilage defect and receives theshaped allograft plug, a shaped drill bit, burr, or cutting disc can beemployed. The shape and dimensions of the drill bit, burr or cuttingdisc, which will determine the shape and dimension of the formed cutout,may correspond to the allograft that is to be transplanted. Anembodiment of such a drill bit 200 is illustrated in FIG. 10. Disposedalong the central axis of the drill bit 200 is a tube or cannula 202adapted to receive the guide pin. The drill bit 200 also includes acircular counter-bore forming element 204 and a conical-shaped cuttingbody 206 extending from the counter-bore forming element. The surface ofthe counter-bore forming element 204 and the cutting body 206 caninclude flutes or other suitable cutting structures. In otherembodiments, to produce differently shaped cutouts, a different drillbit, burr, or cutting disc can be utilized. For example, referring toFIG. 11, there is illustrated a cannulated drill bit 210 having acircular counter-bore forming element 214 and a cylindrical cutting body216.

In use, referring to FIG. 12, the conically cannulated drill bit 200 (orburr or cutting disc when used) is slid onto the guide pin 184 andplaced proximate the host bone 190 such that the cutting body 204 isproximate the cartilage defect. The drill bit 200 can be rotated asindicated, either by hand or by a powered device, to cut into and removethe cartilage defect and the associated bone material thereby formingthe cutout. Where desirable, lubrication can be supplied to facilitatecutting. Referring to FIG. 13, the shape of the cutout 220 formed intothe host bone 190 will correspond to the shape of the drill bit usedincluding having a conical void 222 and a circular counter bore 224proximate the surface of the condyle 192. As will be appreciated, whenthe cannulated drill bit 210 illustrated in FIG. 11 is used, the formedcutout will have a corresponding shape including a circular counter-boreand a cylindrical void. In various embodiments, the shaped drill bits,burrs, and cutting disc can be used to make finishing cuts withdifferent devices used to make initial cuts into the recipient site.

Referring to FIG. 14, a correspondingly shaped conical allograft plug140 can be inserted into the shaped cutout 220 at the recipient siteusing a tamp 228 if necessary. Preferably, the allograft plug 140 andcutout 220 are sized to provide a close fit and, more preferably, aslight press fit, when engaged. Once properly inserted, the shapedcancellous stalk 144 is received deep into the cutout 220 and thusfunctions to anchor the allograft plug 140 to the host bone 190.Additionally, the cartilage plate 142 will be accommodated in thecounter bore 224 such that the healthy cartilage of the allograft plug140 aligns with the healthy cartilage on condyle 192 of the host bone190. Overtime, the cancellous tissue and cartilage plate willpermanently graft with the healthy bone tissue.

While inserting the allograft with a tamp is a common method, any othersuitable method can be employed. For example, referring to FIG. 15, amethod of implanting a conically shaped allograft plug 140 by the use ofsutures is illustrated. According to the method, a pair of parallelholes 230 are cut into the outline of the cutout 220 and through to theopposite side of the host bone 190. A third hole 232 is cut transverselyacross the cancellous stalk 144 of the conical allograft plug 140. Aflexible suture 234 or line can be run through the hole 232 in thecancellous stalk 144 with the ends of the suture run through holes 230in the cutout 220 and out the opposite side of the host bone 190. Aswill be appreciated, pulling the ends of the suture 234 through holes230 will draw the allograft plug 140 tightly into the cutout 220. Itwill be appreciated that any of the foregoing implantation procedurescan work for any of the various shaped allograft plugs and correspondingcutouts.

Preparing the recipient site and removing and shaping an allograft plugfor transplanting into the recipient site can occur simultaneously or,in some embodiments, the allograft plug can be removed and shaped inadvance of preparing the recipient site. Moreover, the preparation of anallograft plug can occur at a different location than the where theinsertion of the allograft plug is to occur. To preserve an allograftplug prior to insertion, the allograft plug can be cryogenicallypreserved. This is an alternative to preparing and transplanting a freshallograft plug.

Though the foregoing procedures for preparing and transplanting a shapedallograft plug can be conducted with any common medical instruments, ina further aspect of the invention, various special instruments andtools, in addition to the template and the shaped drill bit, burr, orcutting discs, are provided. For example, to produce the shapedallograft plug illustrated in FIG. 2 from a donor bone, a guide plate240 as illustrated in FIG. 16 can be used to guide various crown sawcuts into a donor bone 242. The guide plate includes a generallyrectangular base plate 244 that is curved or cambered to fit on acondyle of the donor bone and from one surface of which projects acircular guide cylinder 246. The guide cylinder 246 defines a hollowbore 248 of a first diameter that is disposed through the base plate244. Slidably receivable in the guide cylinder 246 is a smaller secondguide cylinder 250 through which is disposed a second hollow bore 252 ofa second, smaller diameter. The guide plate 240 also includes aplurality of short sharp teeth 254 projecting from a surface of the baseplate 244 opposite the guide cylinder 246.

In use, the guide plate 240 with the second guide cylinder 250 insertedis attached to the donor bone 242 on a surface diametrically opposite ofthe donor site 243. The teeth 254 help attach the guide plate to thedonor bone 242 and can be inserted into the donor bone by thumb pressureor a light tamp. To produce a first cut into the donor bone 242, atubular crown saw having a diameter slightly less than diameter of thesecond hollow bore 252 of the guide plate 240 is inserted through thesecond hollow bore and into the donor bone. Preferably, the first cut ismade into the donor bone 242 from the location of the guide plate 240opposite the donor site 243 to a point a proximate the cartilage plateof the donor site and more preferably only a few millimeters from thecartilage plate. The second, smaller guide cylinder 250 is then removedfrom the guide plate 240. A second crown saw, larger than the firstcrown saw but with a diameter adapted to be slidably received into thefirst hollow bore 248 of the guide plate 240 is inserted through thefirst hollow bore and across the donor bone 242, thereby detaching aportion of bone tissue 258 from the donor bone. The detached bone tissuecan then be trimmed to a desired length, for example, as measured fromthe cartilage plate to the cancellous tissue, to produce the allograftplug 130 having the cylindrical cancellous stalk 134 as illustrated inFIG. 2. Hence, the guide plate helps avoid injury to adjacent normalcartilage on the donor bone. Furthermore, the guide plate 240 can beused in conjunction with a clamping device of the type illustrated anddescribed with respect to FIG. 1. In other embodiments, the guide plate240 can be used with only the first guide cylinder 246 and the second,larger diameter crown saw to produce a cylindrical allograft plug thatcan be subsequently shaped.

To produce an allograft plug having a conical shaped cancellous stalk,as illustrated in FIG. 3, a cannulated burring shell can be used inconjunction with a specially adapted sleeve to further remove cancelloustissue from an allograft plug having a cylindrically—shaped stalk.Referring to FIG. 17, the cannulated burring shell 260 has a hollowconical shell body 262 with a guide aperture 264 disposed through thetip of the cone to provide the cannulated feature. The cannulatedburring shell 264 can also include a circular burring disk 266 thatextends annularly outward from the base of the conical shell body 262.The interior surface of the conical shell body 262 and the underside ofthe burring disc 266 are adapted to grate or remove cannellous bonetissue.

In order to utilize the cannulated feature of the burring shell tofacilitate proper shaping of the conical stalk, referring to FIG. 1 ,the specially adapted sleeve 270 is first placed about the cylindricalallograft plug 130. The sleeve 270 includes a tubular sleeve body 272and a base plate 274 having a centrally located guide aperture 276disposed therein. The sleeve 270 is placed about the allograft plug 130such that the tubular sleeve body 272 receives the cylindricalcancellous stalk 134. Another elongated guide pin 278 is insertedthrough the guide aperture 276 and partially into the cancellous tissueof the stalk 134 as illustrated. Due to the concentric relation of theguide aperture and the tubular sleeve body 272, the guide pin 278 willbe concentrically aligned within the cancellous stalk. The sleeve 270can then be removed and the cannulated burring shell 260 of FIG. 17, viaits guide aperture 264, slide onto the guide pin so that the shell body262 aligns with the cylindrical cancellous stalk. As can be appreciated,rotation of the cannulated burring shell 260 will remove cancelloustissue from the stalk and thereby form the conical shape. Furthermore,the burring disk 266 can remove or smooth the cancellous tissue on theunderside of the allograft plug cartilage plate.

To handle a shaped allograft plug, especially a cylindrically orconically shaped plug, a pair of specially configure forceps can beprovided. Referring to FIG. 19, the forceps 280 can include first andsecond lever arms 282, 284 that intersect and are pivotally joined at apivot point 286. To grasp and manipulate the forceps, there is formed atthe proximal end of each lever arm an eyelet 288 that can accommodate anoperators fingers. Traversing the first lever arm 282 is a locking arm290 that can engage a locking mechanism 292 on the second arm 284 so asto control and fix articulation of the forceps 280. The forceps 280 canbe made from any suitable material such as, for example, stainlesssteel.

Formed at the working ends of the first and second lever arms 282, 284are curved or semicircular clamps 294, 296. The clamps 294, 296 can bejoined to the respective lever arms 282, 284 at any suitable angle suchas, for example, in-line with the lever arms or at right angles with thelever arms. To prevent damaging the allograft plug, a suitable softmaterial 298 such as an elastomer can be coated onto the clamps 294,296. Preferably the elastomer material can be silicone rubber. Hence,when handling a cylindrical or conical allograft plug, the curved clamps294, 296 can be placed around the cartilage plate or cancellous stalkwith the elastomer 298 protecting the bone tissue.

To produce a rectilinear shaped allograft plug, such as the rectangularplug illustrated in FIG. 4, a special template 300 as illustrated inFIGS. 20 and 21 can be used. The template 300 includes a plate 302having a cambered or curved shaped to adapt the plate for attachment tothe condyle surface of a donor bone. Protruding from one surface of theplate 302 are a plurality of sharp teeth 304 to assist in attaching thetemplate to the donor bone. The template 300 can further include anengagement structure 306 on the plate surface opposite the protrudingteeth 304 to engage a detachable handle as described above. Furthermore,while the illustrated template 300 has a rectangular shape, in otherembodiments the template can have other suitable shapes depending uponthe shape of the allograft plug desired.

To actually remove the allograft plug, there is disposed through theplate 302 and within the perimeter outlined by the sharp teeth 304 aplurality of elongated cut slots 310 that are adapted to accommodate aosteotome, chisel, oscillating saw, or other cutting device. To producea rectangular allograft plug, the illustrated cut slots 310 are arrangedrectangularly. However, in other embodiments, to produce other shapedallograft plugs, such as triangular, the cut slots can be arranged inother patterns, such as triangularly. The cut slots 310 are furthermoredisposed into the template 300 on a converging angle such that, when acutting device is inserted through the cut slots and into the donorbone, the cuts being made will intersect at a point in the cancellousbone tissue. Intersecting the cuts will detach the allograft plug fromthe donor bone and simultaneously shape the allograft plug and itscancellous stalk. Hence, locating the cut slots 310 within the outlineof the teeth 304 enables insertion of the teeth into the donor bonewithout damaging the healthy cartilage on allograft plug.

To prepare a recipient site for receiving an rectilinear allograft plug,a template 320 as illustrated in FIG. 22 can be used. The plate 322 ofthe template 320 is similar in shape and configuration to the template300 of FIGS. 20 and 21 and also includes a plurality of cut slots 330disposed angularly there through. To form a cutout in the host bone, thetemplate 320 can be attached to the host bone at a locationcorresponding to a cartilage defect by utilizing the sharp teeth 324protruding from the plate 322. To avoid damaging healthy cartilage onthe host bone, the cut slots 330 are preferably located outside of theoutline of the teeth 324. After attachment, various suitable cuttingdevices can be inserted through the cut slots 330 and into the donorbone to form the cutout. In an embodiment, to enable installation of theguide pin into the recipient site for aligning subsequent operations,the template 320 can have a guide aperture 328 disposed through theplate 322 generally central of teeth 324 and the cut slots 330.

As will be appreciated from the foregoing, the procedures andinstruments described may also be applicable to the preparation andtransplantation of a shaped autograft plug. For example, the removal,shaping, and insertion of an autograft plug from a host site and into arecipient site within the same patient is readily applicable withrespect to rectilinear autograft plugs and can be performed using thesame instruments.

All references, including publications, patent applications, andpatents, cited herein are hereby incorporated by reference to the sameextent as if each reference were individually and specifically indicatedto be incorporated by reference and were set forth in its entiretyherein.

The use of the terms “a” and “an” and “the” and similar referents in thecontext of describing the invention (especially in the context of thefollowing claims) are to be construed to cover both the singular and theplural, unless otherwise indicated herein or clearly contradicted bycontext. The terms “comprising,” “having,” “including,” and “containing”are to be construed as open-ended terms (i.e., meaning “including, butnot limited to,”) unless otherwise noted. Recitation of ranges of valuesherein are merely intended to serve as a shorthand method of referringindividually to each separate value falling within the range, unlessotherwise indicated herein, and each separate value is incorporated intothe specification as if it were individually recited herein. All methodsdescribed herein can be performed in any suitable order unless otherwiseindicated herein or otherwise clearly contradicted by context. The useof any and all examples, or exemplary language (e.g., “such as”)provided herein, is intended merely to better illuminate the inventionand does not pose a limitation on the scope of the invention unlessotherwise claimed. No language in the specification should be construedas indicating any non-claimed element as essential to the practice ofthe invention.

Preferred embodiments of this invention are described herein, includingthe best mode known to the inventors for carrying out the invention.Variations of those preferred embodiments may become apparent to thoseof ordinary skill in the art upon reading the foregoing description. Theinventors expect skilled artisans to employ such variations asappropriate, and the inventors intend for the invention to be practicedotherwise than as specifically described herein. Accordingly, thisinvention includes all modifications and equivalents of the subjectmatter recited in the claims appended hereto as permitted by applicablelaw. Moreover, any combination of the above-described elements in allpossible variations thereof is encompassed by the invention unlessotherwise indicated herein or otherwise clearly contradicted by context.

1. A transplantable osteochondral allograft plug for repairing acartilage defect at a recipient site in a host bone, the allograft plugcomprising: a cartilage plate having a first perimeter; and a cancellousstalk extending from the cartilage plate, the cancellous stalk having asecond perimeter reduced in cross-section with respect to the firstperimeter.
 2. The osteochondral allograft of claim 1, wherein the firstperimeter of the cartilage plate is generally circular.
 3. Theosteochondral allograft of claim 2, wherein the cancellous stalk taperswith respect to the cartilage plate.
 4. The osteochondral allograft ofclaim 2, wherein the cancellous stalk is conical or cylindrical.
 5. Theosteochondral allograft of claim 1, wherein the first perimeter of thecartilage plate is generally rectangular.
 6. The osteochondral allograftof claim 5, wherein the second perimeter is generally rectangular. 7.The osteochondral allograft of claim 1, wherein the first perimeter ofthe cartilage plate is generally triangular.
 8. The osteochondralallograft of claim 7, wherein the second perimeter is a generallytriangular pyramid.